Electric current rectifier



Dec. 13, 1932. s. RUBEN ELECTRIC CURRENT RECTIFIER Filed July 28, 1928ELECTRO POSITI VE ELECTRONEGATIVE ALLOY avwentoz METALLIC COUMPOUND OFVT GRouP "0 Cu 5 E Patented Dec. 13, 1932 UNITED STATES PATENT OFFICE-SAMUEL RUBEN, OF NEW YORK, N. Y., ASSIGNOR TO RUBEN RECTIFIERCORPORATION, OF ENGLEWOOD, NEW JERSEY, A CORPORATION OF DELAWAREELECTRIC CURRENT RECTIFIER Application filed July as,

This invention relates to electric current rectifiers and the like whichemploy asymmetric couples of the dry surface-contact variety.

Rectifiers of this type are characterized by the use of a body ofrelatively electropositive material, employed as one electrode element,disposed in electrical contact with a body of relatively electronegativematerial employed as the other electrode element. Such rectifiers dependfor their operation upon the resistance and inverse current-blockingcharacteristics of the film which forms as the result of electrochemicalaction. Rectifiers of this character, known to the prior art, have beenlow in efliciency andlimited in their application to small currents,becoming-inoperative after short periods of use.

b The present invention has for its object generally to provide animproved device of.

the character described, which is efficient, economical and readilymanufactured, and which, when operating, has a substantiallyinappreciable period of film-formation.

More specifically an object is to provide \an improved electropositiveelectrode element for cooperating with the electro-negative electrodeelement in devices of the character described, particularly where theelectronegative electrode element is a compound of the sixth periodicgroup, in such manner as greatly to reduce and substantially toeliminate the period heretofore required for film formation at thejunction, so that there is a substantially instantaneous direct currentresponse at all times.

Other objects of the invention will in part be obvious and will in partappear hereinafter. t

The invention accordingly comprises the features of construction,combinations of el ements, and arrangement of parts, which will beexemplified in the constructions herein after set forth and the scope ofthe application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the inventionreference should be had to the following detailed description taken inconnectionwith the accompanying drawing, in which:

' volt, 60-cycle source of alternating current.

1928. Serial No. 295,971.

Figure 1 shows diagrammatically a rectifying unit arranged for batterycharging service constructed in accordance with the present invention;and

. Fig. 2 is an enlarged cross-section of the cooperating electrodeelements employed in the construction of units of the present invention,as shown in Fig. 1, the composition of the electrodes beingschematically illustrated. I

Referring now to the drawing and particularly to Fig. 2, 10 denotes anelectronegative electrode element against which is disposed anelectropositive electrode element 11. These elements are cooperativelyarranged in contact to have a junction shown at 12 where the inversecurrent-blocking film is formed, thereby constituting the elements of anasymmetric couple. A rectifying unit is made by operatively assemblingone or more asymmetric couples, for example, as shown in Fig. 1. Here aunit is illustrated which comprises two groups of two couples each, thegroups being inverted with respect to each other on opposite sides ofthe central conducting plate 13. At the outer ends of the groups ofelectrodes there are secured terminal plates 14, preferably in the formof standards, which are held in place by a rivet 15 passing therethroughinsulated from the couples, but conductively connected to the terminalplates 14, this construction being substantially the same construct-ionas that shown in my prior Patent No. 1,649,742, patented November 15, i1927. Between the head and nut on the bolt 15 and the terminal plates 14dished washers 16 are interposed through which the bolt 15 resilientlyapplies its pressure to the plates and thence to the asymmetric couplesheld therebetween. Disposed intermediately of the groups of couples, ateach side of the plate 13, ar terminal plates 17 which provideconnecting terminals for the alternating current input supnlied from anyconvenient source of low voltage, for example, the secondary of thetransformer shown at 18, which is a step-down transformer whose primaryis indicated at 19 supplied from commercial source of alternatingcurrent, such as a 110- 'minum, magnesium or silicon.

The rectifying unit thus constructed of inverted groups of couples is aconvenient mechanical embodiment of the four asymmetric couples hereemployed, arranged in a bridge circuit. Here the terminal plates 17comprise one diagonal of the bridge, while the terminal plate 13 and thebolt 15 comprise the other diagonal. Hence the direct current outputconnections for charging a storage battery, such as shown at B, areconnected respectively to the plates 14 and the plate 13.

In the practice of the present invention the electronegative electrodeelement as shown at 15 is any highly electronegative body whichcooperates with the electropositive electrode element, there beingsufficient resistance at the junction to form the inversecurrentblocking film from the energy supplied by the voltage drop at thejunction, as set forth in my co-pending applications, Serial No.

38,780, filed June 22, 1925, and Serial No..

113,009, filed June 1 1926. A metallic compound of the elements of thesixth periodic group is sufficiently electronegative in theelectrochemical series to provide an operative electrode element. Themetallic component of the electronegative electrode element may be oneor more metals compounded with one or more of the elements of the sixthperiodic group in the table of chemical elements as taught in myco-pending applications, Serial No. 51,524, filed August 20, 1925, andSerial No. 69,215, filed November 16, 1925. By way of illustrativeexample,.the

velectrone gative electrode element will here be considered a maximumvalent compound of sulphur with copper,such as cupric sulphide.

The electropositive electrode element, here employed, is not a simpleelectropositive metallic element but an alloy, the components of whichare highly electropositive and so chosen that the work-function at thejunction is materially reduced. This may be achieved by selecting arelatively heavy electropositive metal of the copper family of theperiodic table of chemical elements as a matr1x and alloying it with alighter film-forming electropositive element chosen from the second.third and fourth groups in the periodic table of chemical elements, suchas alu- A suitable alloy for this purpose has as the matrix a metal suchas copper or silver. The following is an example of an alloy whichhasbeen ascertained -to have a suitable composition:

By weight Copper 80% Magnesium 20% The lighter constituent given in theabove example is substantially uniformly dispersed in the copper matrix.and while magnesium is the only dispersed constituent named in the 'theother film-forming chemical elements chosen from the second, third, andfourth periodlc groups.

The amount of the dispersed constituent may likewise be varied withinlimits from that given in the above example; it having been ascertainedthat the lighter constituent may be taken within the limits of from 5 to25% of the whole by weight in order to obtain the substantiallyinstantaneous recti ying effect herein set forth.

An electropositive electrode element having this composition is adoptedwhen in seiw ice with an electronegative electrode element of cupricsulphide to operate with high-current densities and otherwise showsexcellent characteristics, is highly efiicient, and requires a veryshort period of time (usually materially less than a half-cycle) forfilm formation. The alloy described above has mechanical durability,resistance to a tendency to disintegrate in the presence of moisat thejunction whereby the energy required to beexpended at the junction inthe formation of the inverse current-blocking film is greatly reducedwith the result that the filmforming characteristics. of the couple arealmost instantaneous, so that the direct current response therefrom doesnot lag materially behind in supplying current in the manner heretoforeexperienced with certain types of rectifiers. This laggingcharacteri'stic may be described as film-forming hysteres'is.

It is also to be observed that by the use of an alloy electrode of thepresent invention the need in rectifiers of the dry type for aninterposed resistance layer of a depth or extent heretofore customarilyused is substantially gone, since the energy required for film formationappears to be reduced. This results also in reducing the internalresistance characteristics of the rectifier.

The work-function above referredto is not necessarilv the technicalwork-function generally implied when considering the energy necessary toovercome the attractive forces at the surface of bodies where electronic conduction is involved. The term as herein used, however, isintended to inu'fl s enerally the energy consumed in operati'vely p 'i.e. the storage battery B in the instance relatively electropositive andelectronegative ,ployed, so that in case there is a tendency toward filmdisintegration at any point in the film at the junction, it issubstantially instantly repaired and a full voltage direct currentsupply is had at all times. 'Also it is noted that, by reason of the useof the bridge connection of the asymmetric cells in the rectifying unit,the rectification of both halves of the alternating current impulses isnot only accomplished but also the load,

shown, is in series between two asymmetric cells one of which does therectifying while the other at'the instant rectification serves as abuffer, or cut-out.

Since certain changes may be made in the above construction and,different embodiments of the invention could be made without departingfrom the scope thereof, it is intended that all matter contained in theabove description or shown in the accompanying drawingshall-beinterpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which as amatter of language might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. In electric current rectifiers and the like, of the drysurfacecontact variety, an asymmetric couple arranged to havesubstantially uniform unilateral conductivity, which compriseselectropositive and electronegative electrode elements adj acentlydisposed to have a rectifying junction therebetween, saidelectropositive electrode element being an alloy of an electropositivemetal of the copper family of the periodic table of chemical elementswith a film-forming electropositive chemicalelement, saidelectronegative electrode element being a metallic compound with achemical element of the sixth periodic group.

2. In electric current rectlfiers and the like, of the dry surfacecontact variety, an asymmetric couple arranged to have substantiallyuniform unilateral conductivity, which comprises electropositive andelectronegative electrode elements adj acently disposed to have arectifying junction therebetween, said electropositive. electrodeelement being an alloy having a matrix of an electropositive metal ofthe copper family of the periodic table of chemical elements and afilm-forming electropositive chemical element homogeneously distributedtherein, said electronegative electrode element being a metalliccompound with a chemical element of the sixth periodic.

group.

3. In electric current rectifiers and the like, of the dry surfacecontact variety, an asymmetric couple arranged to have substantiallyuniform unilateral conductivity, which com-.

prises electropositive and electronegative electrode elements adjacentlydisposed to have a rectifying junction therebetween, saidelectropositive electrode. element being an alloy of an electropositivemetal of the copper family of the periodic table of chemical elementswith a film-forming electropositive metallic element chosen from thesecond, third and fourth periodic groups, said electronegative electrodeelement being a metallic compound with sulphur.

4. In electric current rectifiers and thelike, of the dry surfacecontact variety, an asymmetric couple arranged to have substantiallyuniform unilateral conductivity, which commetric couple arranged to havesubstantially I uniform unilateral conductivity','which compriseselectropositive and electronegative electrode elements adjacentlydisposed to have a rectifying junction therebetween, saidelectropositive electrode element be1ng an alloy having a copper matrixand asubstantial amount of magnesiumhomogeneously disbursed therein,said electronegative electrode element being a copper compound with achemical element of the sixth periodic group. I q

6. In electric current rectifiers and the like, of the dry surfacecontact variety, an asymmetric couple arranged to have substantiallyuniform unilateral conductivity, which comprises electropositive andelectronegative electrode elements adjacently disposed to have arectifying junction therebetween, said electropositive electrode elementbeing an alloy having a copper matrix and from about 5 to 25% ofmagnesium homogeneously disbursed therein, said electronegativeelectrode element being a maximum valent metallic compound with achemical element of the sixth periodic group.

7 In electric current rectifiers and the like, of the dry surfacecontact variety, an asymmetric couple arranged to have substantiallyuniform unilateral conductivity, which comprises electropositive andelectronegative electrode elements adj acently disposed to have arectifying junction therebetween, said electropositive electrode elementbeing an alloy havin a copper matrix and from about 5 to 25% 0 magnesiumhomogeneously disbursed therein, said electronegative electrode elementbeing a maximum valent compound of copper with sulphur. I

8. In electric current rectifiers and the like, of the dry surfacecontact variety, an asymmetric couple which comprises electropositiveand electronegative electrodes operatively disposed to have a rectifyingjunction therebetween, said electropositive electrode being an alloycompounded from copper with a film-forming electropositive chemicalelement and adapted to reduce the work-function at the junction of saidelectrodes, Whereby substantially instantaneous film formation is had atthe junction of said electrode elements.

9. In electric current rectifiers and the like, of the dry surfacecontact variety, an asymmetric couple which comprises electropositiveand electronegative electrodes operatively disposed to have a rectifyingjunction therebetween, said electropositive electrode coms prising analloy of copper with magnesium taken substantially in the amount of 20%of the whole by weight whereby the work-function at the junction of theelectropositive and electronegative electrodes appears to besubstantially reduced.

10. In electric current rectifiers and the like, of the dry surfacecontact variety, an asymmetric couple arranged to have substantiallyuniform unilateral conductivity, which comprises electropositive andelectronegative electrode elements adj acently disposed to have arectifying junction therebetween, said electropositive electrode elementbeing an alloy of copper with a relatively light highly electropositivemetal, the electronegative electrode element comprising a compound ofcopper with sulphur.

In testimony whereof I afiix my signature.

SAMUEL RUBEN.

